Providing reliable and efficient VoIP over WCDMA

The notion of offering VoIP service over mobile networks is not new. The 3GPP has been discussing this topic for years, but has yet to define an actual implementation, in part due to a lack of suitable radio access technology. Interest in this technology generally falls into one of two main groups or drivers: • rapid growth in the number of VoIP users on the internet; and • desire on the part of mobile operators to make their businesses more efficient and profitable. Compared with circuit-switched voice service, the main end-user advantage of VoIP is the ease with which one can enrich the basic voice service with multimedia services, such as messaging and video during a VoIP session. A continuously growing number of services will influence and possibly change the way people communicate. The addition of presence information, for example, will help determine the form of communication that users employ. Moreover, in the middle of an ongoing session, end users might change from one form of communication to another by adding video to a voice session. Improved end-user flexibility will also probably lead to an increase in traffic and operator revenues. The advent of VoIP enables established operators to converge their networks into a single all-IP network and to lower their overall operating costs. Similarly, newcomer operators solely need one network for every type of communication (voice and data), which means smaller investments. Being able to deliver every media component over a unified IP infrastructure changes the way one creates and deploys services. Indeed, it changes the very nature of the IP networks themselves. One price to pay for having this vastly more flexible service is the requirement to transfer IP headers all the way to the recipient (receiving client), which results in a larger total bit rate. Making VoIP over mobile systems into an efficient service with the quality and coverage end users have